Extreme-climate instances are on the increase, waste is accumulating, groundwater is running out or is polluted, oil is going to become scarce, and controlling it is the cause of increasingly violent conflicts, whether in Iraq or in Chechnya. At the same time, the capacity of the current economic system to meet social needs is increasingly disputed.

Global inequalities are becoming deeper, and if part of Asia is coming out of underdevelopment, it is doing so by adopting a lifestyle that devours nonrenewable resources. In short, and everyone (or nearly everyone) now agrees: we are running into a wall and we have to change our form of development. Not in a century, but in the next few years. But how can we go about it? An increasingly vivid debate is opposing the advocates of "sustainable negative growth," which would organize the recession of monetary economy, and those of "sustainable development," designed to reconcile growth and ecology.

This article presents the stakes involved in the controversy between the possible positions in favor or against sustainable development or negative growth in a context of environmental emergency on the one hand, and of third-world populations eager for comfort and consumption as well as those of the first world who do not wish to abandon them. It also sets out the limits of the second option and the difficulty of educating citizens for its implementation.